At this point, in my controller i am now able to get to the User.Identity. The problem then became how to i set Form Collection variables. Setting

builder.Form.Add("testvar","1");

no longer worked. It seemed that now I had to access via

controller.HttpContext.Request.Form.Add("testvar","1)

This seemed to work, but at this point, i was no longer using builder(TestControllerBuilder) above.

I then had to mock Server which raised up more issues. How can I continue to use builder but use mocks or stubs for httpContext, HttpRequest, Server etc. I was sort of expecting that builder would have methods for setting expected values for HttpRequest, Server etc.